The role of external radiotherapy in patients treated with permanent prostate brachytherapy

To examine the difference in Prostate Specific Antigen (PSA)-Relapse Free Survival (RFS) in patients (pts) with prostate cancer treated with permanent prostate brachytherapy (PPB) alone (monotherapy) or combined modality PPB and external radiotherapy (CMT) by a matched pair analysis. There were 1476 pts who were treated loosely based on the American Brachytherapy Society criteria for monotherapy or CMT. PSA-RFS was based upon the Kattan modification of the ASTRO consensus panel definition. A computer generated matching process was undertaken to produce two equally weighted pairs of patients divided by treatment methodology and Kaplan-Meier PSA-RFS curves were generated and compared by chi(2) testing. All pts were treated between 1992 and 2000 with a 6-y PSA-RFS of 81.9%. The median follow-up was 34.7 months. Patients treated with CMT presented with higher pre-treatment PSA values, Gleason sum score, clinical stage, risk classification, and were more likely to be treated with neoadjuvant hormones. A matched-pair analysis with 314 pts in each group was created stratified by the addition of neoadjuvant hormones, Gleason score sum and the pretreatment PSA value. Actuarial 5-y PSA-RFS was 77.0% for the monotherapy group and 81.1% for the combined therapy group (P=0.54).chi(2) testing by pretreatment PSA value, Gleason score sum, risk stratification, isotope and the addition of neoadjuvant hormones failed to identify any group with a significant difference in 5-y PSA-RFS. In conclusion, this retrospective study presents a large cohort of patients treated with PPB that failed to identify a significant advantage for the addition of combined therapy. A matched pair analysis performed also failed to identify any significant difference based on treatment modality.